Ok let me list a few things, 1st Keyblades have types, they are easy light or dark depending open what they represent. 2nd Since keyblades have types and can represent different things there is more then one keyblade. In most cases, since the keyblade can change as it travels between the worlds it is not so unlikely that each world hosts its own keyblade. The keychain allows the keyblade to change to the keyblade that represents that world. Also the keyblade can also reprsent feelings, like oathkeeper and obvilion. 4th What I just said might make it seem that a keyblade can be made by anyone. But infact it is most logical to expect a keyblade only is made during the event of a crisis or when the worlds are about to undergo some seriouse changes. Most likely the type of keyblade is usually the opposite direction of where most of the worlds are heading to. So if all worlds are being taken over by heartless the keyblade would be light and choose a wielder who is light. Riku was leaning towards the dark but was stronger then Sora's heart when the keyblade was going to choose him, but Ansem nudged Riku towards the path of darkness. Note it was still Riku's choice to do so. 5th There can be more then one keyblade master. This is obviouse bacuse there is 1) more then one person with a stronge heart 2) three people have keyblades of there own, sora, bhk(well maybe there his?), and mickey 3) more then one type of keyblade. I do know how the keyblades are made, the user has to go through some type of trail. Sora having to fight a big ass heartless, Bhk having to fight a big ass N.E.O, mickey having to find the light within the darkness. Where they come from I don't know and it really doesn't matter. The keyblades just appear when the worlds are at a climax. I think thats enough to know.